Catheter pump with access ports

ABSTRACT

A securing assembly for connecting a drive assembly to a driven assembly of a catheter pump includes a motor housing, a flow diverter housing, and a flow diverter positioned within the flow diverter housing, wherein one of the flow diverter or the flow diverter housing includes a securement device. The securing assembly also includes a cap coupled between the motor housing and the flow diverter housing. The cap includes a central opening and a locking recess extending circumferentially about the central opening. Insertion of the flow diverter into the central opening causes securement device to engage the locking recess.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No. 15/794,609 filed on Oct. 26, 2017, now issued U.S. Pat. No. 10,576,192, which is a Continuation of U.S. patent application Ser. No. 14/687,382 filed on Apr. 15, 2015, now issued U.S. Pat. No. 9,827,356, which claims the benefit of priority to U.S. Provisional Patent Application No. 61/979,952 filed on Apr. 15, 2014, each of which is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

This application is directed to catheter pumps for mechanical circulatory support of a heart.

Description of the Related Art

Heart disease is a major health problem that has high mortality rate. Physicians increasingly use mechanical circulatory support systems for treating heart failure. The treatment of acute heart failure requires a device that can provide support to the patient quickly. Physicians desire treatment options that can be deployed quickly and minimally-invasively.

Intra-aortic balloon pumps (IABP) are currently the most common type of circulatory support devices for treating acute heart failure. IABPs are commonly used to treat heart failure, such as to stabilize a patient after cardiogenic shock, during treatment of acute myocardial infarction (MI) or decompensated heart failure, or to support a patient during high risk percutaneous coronary intervention (PCI). Circulatory support systems may be used alone or with pharmacological treatment.

In a conventional approach, an IABP is positioned in the aorta and actuated in a counterpulsation fashion to provide partial support to the circulatory system. More recently minimally-invasive rotary blood pump have been developed in an attempt to increase the level of potential support (i.e., higher flow). A rotary blood pump is typically inserted into the body and connected to the cardiovascular system, for example, to the left ventricle and the ascending aorta to assist the pumping function of the heart. Other known applications pumping venous blood from the right ventricle to the pulmonary artery for support of the right side of the heart. An aim of acute circulatory support devices is to reduce the load on the heart muscle for a period of time, to stabilize the patient prior to heart transplant or for continuing support.

There is a need for improved mechanical circulatory support devices for treating acute heart failure. Fixed cross-section ventricular assist devices designed to provide near full heart flow rate are either too large to be advanced percutaneously (e.g., through the femoral artery without a cutdown) or provide insufficient flow.

There is a need for a pump with improved performance and clinical outcomes. There is a need for a pump that can provide elevated flow rates with reduced risk of hemolysis and thrombosis. There is a need for a pump that can be inserted minimally-invasively and provide sufficient flow rates for various indications while reducing the risk of major adverse events. In one aspect, there is a need for a heart pump that can be placed minimally-invasively, for example, through a 15 FR or 12 FR incision. In one aspect, there is a need for a heart pump that can provide an average flow rate of 4 Lpm or more during operation, for example, at 62 mmHg of head pressure. While the flow rate of a rotary pump can be increased by rotating the impeller faster, higher rotational speeds are known to increase the risk of hemolysis, which can lead to adverse outcomes and in some cases death. Accordingly, in one aspect, there is a need for a pump that can provide sufficient flow at significantly reduced rotational speeds. These and other problems are overcome by the inventions described herein.

Further, there is a need for a motor configured to drive an operative device, e.g., a impeller, at a distal portion of the pump. It can be important for the motor to be configured to allow for percutaneous insertion of the pump's operative device.

SUMMARY OF THE INVENTION

There is an urgent need for a pumping device that can be inserted percutaneously and also provide full cardiac rate flows of the left, right, or both the left and right sides of the heart when called for.

In one embodiment, a catheter pump is disclosed. The catheter pump can comprise an elongate catheter body. An impeller assembly can be coupled to a distal portion of the elongate catheter body. The impeller assembly can comprise an impeller configured to rotate during operation of the catheter pump. The catheter pump can comprise an access channel extending through at least portions of the elongate catheter body and the impeller assembly. The access channel can extend distal the impeller and configured to remain in the portions of the elongate catheter body and the impeller assembly during operation of the catheter pump.

In another embodiment, a method of operating a catheter pump is disclosed. The method can comprise advancing a guidewire to a treatment location in a patient. The method can include disposing a distal end of a guidewire guide tube over the guidewire. The guidewire guide tube can be disposed in a catheter pump comprising a catheter body and an impeller assembly coupled to a distal portion of the catheter body. The method can comprise advancing the impeller assembly, the catheter body, and the guidewire guide tube along the guidewire to position the impeller assembly at the treatment location. The method can include activating the impeller assembly to pump blood while maintaining the guidewire guide tube in the catheter pump.

In one embodiment, a catheter pump is disclosed. The catheter pump can include a catheter assembly. The catheter assembly can include a drive shaft having a proximal end and a distal end. An impeller may be coupled with the distal end of the drive shaft. A driven magnet assembly may be coupled with the proximal end of the drive shaft. The driven magnet assembly can include a driven magnet housing having a driven magnet. The catheter pump can further include a drive system. The drive system can include a motor having an output shaft. The drive system can also include a drive magnet assembly coupled with the output shaft. The drive magnet assembly can include a drive magnet housing with a drive magnet disposed therein. A securement device can be configured to secure the driven magnet housing into engagement with the drive magnet housing during operation of the pump.

In another embodiment, a catheter pump is disclosed. The catheter pump can include a catheter assembly. The catheter assembly can comprise a drive shaft having a proximal end and a distal end. An impeller can be coupled with the distal end of the drive shaft. A rotatable magnet can be coupled with the proximal end. The rotatable magnet can be disposed in a driven magnet housing. Furthermore, the catheter pump can include a drive system comprising a plurality of motor windings configured to induce rotation of the rotatable magnet when the driven magnet housing is engaged with the drive system. A locking device can be configured to be engaged by insertion of the driven magnet housing into an opening of the drive system.

In yet another embodiment, a method is disclosed. The method can include inserting a proximal portion of a catheter assembly containing a magnet into a recess of a drive unit. The method can further include engaging a locking device to secure the proximal portion of the catheter assembly to the drive unit.

In another embodiment, a catheter assembly is disclosed. The catheter assembly can include a catheter body having a proximal portion and a distal portion. An operative device can be coupled to the distal portion of the catheter body. A tip member can be coupled to a distal portion of the operative device. The tip member can have a lumen comprising a first section and a second section connected to the first section. An inner diameter of the first section can be larger than an inner diameter of the second section.

In one embodiment, a catheter pump is provided that includes a catheter assembly and a drive system, and a securement device. The catheter assembly includes a drive shaft, an impeller, and a driven assembly. The drive shaft has a proximal end and a distal end. The impeller is coupled with the distal end of the drive shaft. The driven assembly may be coupled with the proximal end of the drive shaft, the driven assembly is disposed in a driven housing. The drive system includes a motor having an output shaft and a output drive assembly coupled with the shaft. The drive assembly includes a drive housing with at least one magnet disposed therein. The securement device is configured to prevent disengagement of the driven housing from the drive housing during operation of the pump.

In one embodiment, a catheter pump is provided that includes a catheter assembly and a drive system, and a damper. The catheter assembly includes a drive shaft, an impeller, and a driven member. The drive shaft has a proximal end and a distal end. The impeller is coupled with the distal end of the drive shaft. The driven member is coupled with the proximal end of the drive shaft. The drive system includes a motor having an output shaft and a drive member coupled with the output shaft.

In one variant, the catheter pump can have a damper disposed between the drive and driven member. The damper can be configured to isolate the drive member or the motor from vibration in the catheter assembly. The damper can be configured to suppress noise at or around the connection between the drive and drive members.

Preferably, the damper is disposed radially around the output shaft, e.g., completely surrounding the output shaft. The damper can be disposed between separable housings of the catheter assembly and drive system, e.g., abutting a distal face of a drive system housing and a proximal face of a driven member housing disposed on the proximal end of the catheter assembly.

This embodiment can be augmented in some embodiments with a disconnectable coupling between the drive and driven members. For example, a securement device can be configured to permit selective disengagement of these components from each other. The securement device can be configured to prevent disengagement of the driven housing from the drive housing during operation of the pump.

Connection of the drive and driven members can be by the mutual attraction of opposing poles of permanent magnets disposed therein. Alternatively, the driven member can be positioned to be acted upon magnetic fields generated in the winding, e.g., using commutation in the windings. In another embodiment, the drive and driven members are coupled using direct mechanical drive, such as with gears, splines or other abutting surfaces.

In another embodiment, a catheter pump is provided that has a catheter assembly, a drive system, and a locking device. The catheter assembly has a drive shaft that has a proximal end and a distal end. An impeller is coupled with the distal end of the drive shaft. A rotatable magnet is coupled with the proximal end of the drive shaft. The rotatable magnet is disposed in a driven magnet housing. The drive system has a plurality of motor windings configured to induce rotation of the rotatable magnet after the driven magnet housing is engaged with the drive system. The locking device is configured to be engaged by insertion of the driven magnet housing into a portion or recess of the drive system.

Rotation can be induced in the rotatable magnet by the mutual attraction of opposing poles of permanent magnets. The rotatable magnet can be an assembly having one or a first plurality of permanent magnets and one or a second plurality of permanent magnets can be mounted on a shaft of the motor having the motor windings. Pairing of opposite poles of two magnets or of the magnets of the first and second pluralities of permanent magnets can induce rotation that can be transferred to the drive shaft. Alternatively, the rotatable magnet can be positioned to be acted upon magnetic fields generated in the winding, e.g., using commutation in the windings.

In another embodiment, a method is provided. A proximal portion of a catheter assembly containing a magnet is inserted into a recess of a drive unit. A locking device is engaged to secure the proximal portion of the catheter assembly to a distal portion of the drive unit.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of this application and the various advantages thereof can be realized by reference to the following detailed description, in which reference is made to the accompanying drawings in which:

FIG. 1 illustrates one embodiment of a catheter pump configured for percutaneous application and operation;

FIG. 2 is a plan view of one embodiment of a catheter adapted to be used with the catheter pump of FIG. 1;

FIG. 3 show a distal portion of the catheter system similar to that of FIG. 2 in position within the anatomy;

FIG. 4 is a schematic view of a catheter assembly and a drive assembly;

FIG. 4A is an enlarged view of a priming apparatus shown in FIG. 4;

FIG. 5 is a three dimensional (3D) perspective view of a motor assembly as the drive assembly is being coupled to a driven assembly;

FIG. 6 is a 3D perspective view of the motor assembly once the drive assembly has been coupled and secured to the driven assembly;

FIG. 7 is a 3D perspective view of the motor assembly of FIG. 6, wherein various components have been removed for ease of illustration;

FIG. 8 is a plan view of the motor assembly that illustrates a motor, a drive magnet and a driven magnet;

FIG. 9 is a 3D perspective view of a first securement device configured to secure the drive assembly to the driven assembly;

FIGS. 10A-10C are 3D perspective views of a second securement device configured to secure the drive assembly to the driven assembly;

FIG. 11 illustrates a side schematic view of a motor assembly according to another embodiment;

FIGS. 12A-12B illustrates side schematic views of a motor assembly according to yet another embodiment;

FIG. 13 is a side view of a distal tip member disposed at a distal end of the catheter assembly, according to one embodiment;

FIG. 14 is a side cross-sectional view of a distal tip member disposed at a distal end of the catheter assembly, according to another embodiment.

FIG. 15 is a side view of an impeller assembly having a cannula housing, an impeller disposed in the cannula housing, and a tip member, according to various embodiments.

FIG. 16 is a side cross-sectional view of an access channel disposed at a distal end of the catheter assembly, according to another embodiment.

FIGS. 17A and 17B are images of a proximal portion of an access channel, according to some embodiments.

More detailed descriptions of various embodiments of components for heart pumps useful to treat patients experiencing cardiac stress, including acute heart failure, are set forth below.

DETAILED DESCRIPTION I. Overview of System Components

This application is directed to apparatuses for inducing motion of a fluid relative to the apparatus. For example, an operative device, such as an impeller, can be coupled at a distal portion of the apparatus. In particular, the disclosed embodiments generally relate to various configurations for a motor adapted to drive an impeller at a distal end of a catheter pump, e.g., a percutaneous heart pump. The disclosed motor assembly may be disposed outside the patient in some embodiments. In other embodiments, the disclosed motor assembly can be miniaturized and sized to be inserted within the body. FIGS. 1-3 show aspects of a catheter pump 10 that can provide high performance flow rates. The pump 10 includes a motor driven by a controller 22. The controller 22 directs the operation of the motor 14 and an infusion or operating fluid system 26 that supplies a flow of operating fluid or infusate in the pump 10.

A catheter system 80 that can be coupled with the motor 14 houses an impeller within a distal portion thereof. In various embodiments, the impeller is rotated remotely by the motor 14 when the pump 10 is operating. For example, the motor 14 can be disposed outside the patient. In some embodiments, the motor 14 is separate from the controller 22, e.g., to be placed closer to the patient. In other embodiments, the motor 14 is part of the controller 22. In still other embodiments, the motor is miniaturized to be insertable into the patient. Such embodiments allow a drive shaft conveying torque to an impeller or other operating element at the distal end to be much shorter, e.g., shorter than the distance from the aortic valve to the aortic arch (about 5 cm or less). Some examples of miniaturized motors catheter pumps and related components and methods are discussed in U.S. Pat. Nos. 5,964,694; 6,007,478; 6,178,922; and 6,176,848, all of which are hereby incorporated by reference herein in their entirety for all purposes. Various embodiments of a motor are disclosed herein, including embodiments having separate drive and driven assemblies to enable the use of a guidewire guide passing through the catheter pump. As explained herein, a guidewire guide can facilitate passing a guidewire through the catheter pump for percutaneous delivery of the pump's operative device to a patient's heart.

In some embodiments, the guidewire guide can be removable from the patient once the catheter pump is positioned in the anatomy. In other embodiments, the guidewire guide can be configured as an access port or access channel to provide access to the heart while the impeller is rotating. For example, the access channel or guidewire guide may be permanently or non-removably disposed in the catheter pump such that the guidewire guide remains in the catheter pump during operation. In other arrangements, the guidewire guide can remain in the catheter pump and patient during operation but can be removed by the clinician when desired. Providing such an access channel (e.g., a guidewire guide) can enable the clinician to have access to the heart during the procedure for various purposes. For example, one or more sensors can be disposed through the access channel to measure fluid properties during the procedure. Medications or other chemicals may be delivered through the access channel during the procedure. Furthermore, the use of a guidewire guide that remains in the patient during treatment can enable the clinician to reinsert the guidewire to reposition the catheter pump if the catheter pump becomes misaligned during the procedure. It should be appreciated that, although the guidewire guide may be described as permanent or non-removable in various embodiments, this is meant to designate a guidewire guide that is configured to remain in the catheter pump during operation of the catheter pump, even if the guidewire guide is physically capable of being removed from the catheter pump, e.g., by disassembly of the catheter pump and/or by suitable forces being applied to the guidewire guide. Indeed, in various embodiments, the access channel or guidewire guide is configured to be removed from the catheter pump when desired by the clinician.

FIGS. 1-4 show aspects of one embodiment of a catheter pump 10 that can provide high performance flow rates. Various additional aspects of the pump and associated components are similar to those disclosed in U.S. Pat. Nos. 7,393,181, 8,376,707, 7,841,976, 8,535,211, 8,597,170, 8,485,961, 8,591,393, 7,022,100, and 7,998,054 and U.S. Pub. Nos. 2012/0178986, 2013/0303970, 2013/0303969, 2013/0303830, 2014/0012065, and 2014/0010686 the entire contents of which are incorporated herein for all purposes by reference. In addition, this application incorporates by reference in its entirety and for all purposes the subject matter disclosed in each of the following concurrently filed applications: U.S. patent application Ser. No. 14/203,978, entitled “FLUID HANDLING SYSTEM,” and Ser. No. 14/209,889, entitled “CATHETER PUMP ASSEMBLY INCLUDING A STATOR,” filed on Mar. 13, 2014 and PCT Patent Application Nos. PCT/US2014/020790, entitled “FLUID HANDLING SYSTEM,” and PCT/US2014/020878, entitled “CATHETER PUMP ASSEMBLY INCLUDING A STATOR,” filed on Mar. 5, 2014.

FIG. 3 illustrates one use of the catheter pump 10. A distal portion of the pump 10, which can include an impeller assembly 92, is placed in the left ventricle LV of the heart to pump blood from the LV into the aorta. The pump 10 can be used in this way to treat patients with a wide range of conditions, including cardiogenic shock, myocardial infarction, and other cardiac conditions, and also to support a patient during a procedure such as percutaneous coronary intervention. One convenient manner of placement of the distal portion of the pump 10 in the heart is by percutaneous access and delivery using the Seldinger technique or other methods familiar to cardiologists. These approaches enable the pump 10 to be used in emergency medicine, a catheter lab and in other non-surgical settings. Modifications can also enable the pump 10 to support the right side of the heart. Example modifications that could be used for right side support include providing delivery features and/or shaping a distal portion that is to be placed through at least one heart valve from the venous side, such as is discussed in U.S. Pat. Nos. 6,544,216; 7,070,555; and US 2012-0203056A1, all of which are hereby incorporated by reference herein in their entirety for all purposes.

FIG. 2 shows features that facilitate small blood vessel percutaneous delivery and high performance, including up to and in some cases exceeding normal cardiac output in all phases of the cardiac cycle. In particular, the catheter system 80 includes a catheter body 84 and a sheath assembly 88. The catheter body 84 can include an elongate body with proximal and distal end, in which a length of the body 84 enables the pump 10 to be applied to a patient from a peripheral vascular location. The impeller assembly 92 is coupled with the distal end of the catheter body 84. The impeller assembly 92 is expandable and collapsible. In the collapsed state, the distal end of the catheter system 80 can be advanced to the heart, for example, through an artery. In the expanded state the impeller assembly 92 is able to pump blood at high flow rates. FIGS. 2 and 3 illustrate the expanded state. The collapsed state can be provided by advancing a distal end 94 of an elongate body 96 distally over the impeller assembly 92 to cause the impeller assembly 92 to collapse. This provides an outer profile throughout the catheter assembly 80 that is of small diameter, for example, to a catheter size of about 12.5 FR in various arrangements.

In some embodiments, the impeller assembly 92 includes a self-expanding material that facilitates expansion. The catheter body 84 on the other hand preferably is a polymeric body that has high flexibility.

The mechanical components rotatably supporting the impeller within the impeller assembly 92 permit high rotational speeds while controlling heat and particle generation that can come with high speeds. The infusion system 26 delivers a cooling and lubricating solution (sometimes referred to herein as an operating fluid) to the distal portion of the catheter system 80 for these purposes. However, the space for delivery of this fluid is extremely limited. Some of the space is also used for return of the operating fluid. Providing secure connection and reliable routing of operating fluid into and out of the catheter assembly 80 is critical and challenging in view of the small profile of the catheter body 84.

When activated, the catheter pump system can effectively increase the flow of blood out of the heart and through the patient's vascular system. In various embodiments disclosed herein, the pump can be configured to produce a maximum flow rate (e.g. low mm Hg) of greater than 4 Lpm, greater than 4.5 Lpm, greater than 5 Lpm, greater than 5.5 Lpm, greater than 6 Lpm, greater than 6.5 Lpm, greater than 7 Lpm, greater than 7.5 Lpm, greater than 8 Lpm, greater than 9 Lpm, or greater than 10 Lpm. In various embodiments, the pump can be configured to produce an average flow rate at 62 mmHg of greater than 2 Lpm, greater than 2.5 Lpm, greater than 3 Lpm, greater than 3.5 Lpm, greater than 4 Lpm, greater than 4.25 Lpm, greater than 4.5 Lpm, greater than 5 Lpm, greater than 5.5 Lpm, or greater than 6 Lpm.

Another example of a catheter assembly 100A is illustrated in FIG. 4. Embodiments of the catheter pump of this application can be configured with a motor that is capable of coupling to (and in some arrangements optionally decoupling from) the catheter assembly 100A. This arrangement provides a number of advantages over a non-disconnectable motor. For example, access can be provided to a proximal end of the catheter assembly 100A prior to or during use. In one configuration, a catheter pump is delivered over a guidewire. The guidewire may be conveniently extended through the entire length of the catheter assembly 100A and out of a proximal portion thereof that is completely enclosed in a coupled configuration. For this approach, connection of the proximal portion of the catheter assembly 100A to a motor housing can be completed after a guidewire has been used to guide the operative device of the catheter pump to a desired location within the patient, e.g., to a chamber of the patient's heart. In one embodiment, the connection between the motor housing and the catheter assembly is configured to be permanent, such that the catheter assembly, the motor housing and the motor are disposable components. However, in other implementations, the coupling between the motor housing and the catheter assembly is disengageable, such that the motor and motor housing can be decoupled from the catheter assembly after use. In such embodiments, the catheter assembly distal of the motor can be disposable, and the motor and motor housing can be re-usable.

Moving from the distal end of the catheter assembly 100A of FIG. 4 to the proximal end, a priming apparatus 1400 can be disposed over an impeller assembly 116A. As explained above, the impeller assembly 116A can include an expandable cannula or housing and an impeller with one or more blades. As the impeller rotates, blood can be pumped proximally (or distally in some implementations) to function as a cardiac assist device.

FIG. 4 also shows one example of a priming apparatus 1400 disposed over the impeller assembly 116A near the distal end 170A of the elongate body 174A. FIG. 4A is an enlarged view of the priming apparatus 1400 shown in FIG. 4. The priming apparatus 1400 can be used in connection with a procedure to expel air from the impeller assembly 116A, e.g., any air that is trapped within the housing or that remains within the elongate body 174A near the distal end 170A. For example, the priming procedure may be performed before the pump is inserted into the patient's vascular system, so that air bubbles are not allowed to enter and/or injure the patient. The priming apparatus 1400 can include a primer housing 1401 configured to be disposed around both the elongate body 174A and the impeller assembly 116A. A sealing cap 1406 can be applied to the proximal end 1402 of the primer housing 1401 to substantially seal the priming apparatus 1400 for priming, i.e., so that air does not proximally enter the elongate body 174A and also so that priming fluid does not flow out of the proximal end of the housing 1401. The sealing cap 1406 can couple to the primer housing 1401 in any way known to a skilled artisan. However, in some embodiments, the sealing cap 1406 is threaded onto the primer housing by way of a threaded connector 1405 located at the proximal end 1402 of the primer housing 1401. The sealing cap 1406 can include a sealing recess disposed at the distal end of the sealing cap 1406. The sealing recess can be configured to allow the elongate body 174A to pass through the sealing cap 1406.

The priming operation can proceed by introducing fluid into the sealed priming apparatus 1400 to expel air from the impeller assembly 116A and the elongate body 174A. Fluid can be introduced into the priming apparatus 1400 in a variety of ways. For example, fluid can be introduced distally through the elongate body 174A into the priming apparatus 1400. In other embodiments, an inlet, such as a luer, can optionally be formed on a side of the primer housing 1401 to allow for introduction of fluid into the priming apparatus 1400.

A gas permeable membrane can be disposed on a distal end 1404 of the primer housing 1401. The gas permeable membrane can permit air to escape from the primer housing 1401 during priming.

The priming apparatus 1400 also can advantageously be configured to collapse an expandable portion of the catheter assembly 100A. The primer housing 1401 can include a funnel 1415 where the inner diameter of the housing decreases from distal to proximal. The funnel may be gently curved such that relative proximal movement of an impeller housing of the impeller assembly 116A causes the impeller housing to be collapsed by the funnel 1415. During or after the impeller housing has been fully collapsed, the distal end 170A of the elongate body 174A can be moved distally relative to the collapsed housing. After the impeller housing is fully collapsed and retracted into the elongate body 174A of the sheath assembly, the catheter assembly 100A can be removed from the priming housing 1400 before a percutaneous heart procedure is performed, e.g., before the pump is activated to pump blood. The embodiments disclosed herein may be implemented such that the total time for infusing the system is minimized or reduced. For example, in some implementations, the time to fully infuse the system can be about six minutes or less. In other implementations, the time to infuse can be about three minutes or less. In yet other implementations, the total time to infuse the system can be about 45 seconds or less. It should be appreciated that lower times to infuse can be advantageous for use with cardiovascular patients.

With continued reference to FIG. 4, the elongate body 174A extends proximally from the impeller assembly 116A to an infusate device 195 configured to allow for infusate to enter the catheter assembly 100A and for waste fluid to leave the catheter assembly 100A. A catheter body 120A (which also passes through the elongate body 174A) can extend proximally and couple to a driven assembly 201. The driven assembly 201 can be configured to receive torque applied by a drive assembly 203, which is shown as being decoupled from the driven assembly 201 and the catheter assembly 100A in FIG. 4. Although not shown in FIG. 4, a drive shaft can extend from the driven assembly 201 through the catheter body 120A to couple to an impeller shaft at or proximal to the impeller assembly 116A. The catheter body 120A can pass within the elongate catheter body 174A such that the external catheter body 174A can axially translate relative to the catheter body 120A.

In addition, FIG. 4 illustrates a guidewire 235 extending from a proximal guidewire opening 237 in the driven assembly 201. Before inserting the catheter assembly 100A into a patient, a clinician may insert the guidewire 235 through the patient's vascular system to the heart to prepare a path for the operative device (e.g., the impeller assembly 116A) to the heart. In some embodiments, the catheter assembly can include a guidewire guide tube (see FIG. 12) passing through a central internal lumen of the catheter assembly 100A from the proximal guidewire opening 237. The guidewire guide tube can be pre-installed in the catheter assembly 100A to provide the clinician with a preformed pathway along which to insert the guidewire 235.

In one approach, a guidewire is first placed in a conventional way, e.g., through a needle into a peripheral blood vessel, and along the path between that blood vessel and the heart and into a heart chamber, e.g., into the left ventricle. Thereafter, a distal end opening of the catheter assembly 100A or guidewire guide can be advanced over the proximal end of the guidewire 235 to enable delivery to the catheter assembly 100A. After the proximal end of the guidewire 235 is urged proximally within the catheter assembly 100A and emerges from the guidewire opening 237 and/or guidewire guide, the catheter assembly 100A can be advanced into the patient. In one method, the guidewire guide is withdrawn proximally while holding the catheter assembly 100A. The guidewire guide is taken off of the catheter assembly 100A so that guidewire lumens from the proximal end to the distal end of the catheter assembly 100A are directly over the guidewire. In other embodiments, as explained in more detail below, the guidewire guide may be coupled with the catheter assembly 100A such that the guidewire guide is not removed during operation of the catheter pump. In such arrangements, the guidewire guide can act as an access channel to the anatomy.

Alternatively, the clinician can thus insert the guidewire 235 through the proximal guidewire opening 237 and urge the guidewire 235 along the guidewire guide tube until the guidewire 235 extends from a distal guidewire opening (not shown) in the distal end of the catheter assembly 100A. The clinician can continue urging the guidewire 235 through the patient's vascular system until the distal end of the guidewire 235 is positioned in the desired chamber of the patient's heart. As shown in FIG. 4, a proximal end portion of the guidewire 235 can extend from the proximal guidewire opening 237. Once the distal end of the guidewire 235 is positioned in the heart, the clinician can maneuver the impeller assembly 116A over the guidewire 235 until the impeller assembly 116A reaches the distal end of the guidewire 235 in the heart. The clinician can remove the guidewire 235 and the guidewire guide tube. The guidewire guide tube can also be removed before or after the guidewire 235 is removed in some implementations. In other embodiments, as explained below, the guidewire guide tube may remain within the catheter assembly 100A during the treatment procedure.

After removing at least the guidewire 235, the clinician can activate a motor to rotate the impeller and begin operation of the pump.

One problem that arises when using the guidewire 235 to guide the operative device to the heart is that a central lumen or tube (e.g., a guidewire guide) is typically formed to provide a path for the guidewire 235. In some implementations, it may be inconvenient or inoperable to provide a motor or drive assembly having a lumen through which the guidewire 235 can pass. Moreover, in some implementations, it may be desirable to provide the motor or drive assembly separate from the catheter assembly 100A, e.g., for manufacturing or economic purposes. Thus, it can be advantageous to provide a means to couple the drive assembly 203 to the driven assembly 201, while enabling the use of a guidewire guide through which a guidewire may be passed. Preferably, the drive assembly 203 can be securely coupled to the driven assembly 201 such that vibratory, axial, or other external forces do not decouple the drive assembly 203 from the driven assembly 201 during operation. Moreover, the coupling should preferably allow a motor to operate effectively so that the drive shaft is rotated at the desired speed and with the desired torque.

II. Examples of Motor Assemblies

FIG. 5 illustrates one embodiment of a motor assembly 206 as the driven assembly 201 is being coupled to the drive assembly 203. The driven assembly 201 can include a flow diverter 205 and a flow diverter housing 207 that houses the flow diverter 205. The flow diverter 205 can be configured with a plurality of internal cavities, passages, and channels that are configured to route fluid to and from the patient during a medical procedure. As discussed below, an infusate can be directed into the flow diverter from a source of infusate. The infusate is a fluid that flows into the catheter body 120A to provide useful benefits, such as cooling moving parts and keeping blood from entering certain parts of the catheter assembly 100A. The infusate is diverted distally by flow channels in the flow diverter 205. Some of the infusate that flows distally is re-routed back through the catheter body 120A and may be diverted out of the catheter assembly 100A by the flow diverter 205. Moreover, a driven magnet 204 can be disposed within the flow diverter 205 in various embodiments. For example, the driven magnet 204 can be journaled for rotation in a proximal portion of the flow diverter housing 207. The proximal portion can project proximally of a proximal face of a distal portion of the flow diverter housing 207. In other embodiments, the driven magnet 204 can be disposed outside the flow diverter 205. The driven magnet 204 can be configured to rotate freely relative to the flow diverter 205 and/or the flow diverter housing 207. The catheter body 120A can extend from a distal end of the flow diverter housing 207. Further, a drive shaft 208 can pass through the catheter body 120A from the proximal end of the flow diverter housing 207 to the distal end 170A of the elongate body 174A. The drive shaft 208 can be configured to drive the impeller located at the distal end of the catheter assembly 100A. In some embodiments, a distal end of the drive shaft 208 can couple to an impeller shaft, which rotates the impeller.

The drive assembly 203 can include a drive housing or a motor housing 211 having an opening 202 in a cap 212 of the motor housing 211. The motor housing 211 can also have a sliding member 213, which can be configured to couple to the patient's body by way of, e.g., a connector 291 coupled to an adhesive or bandage on the patient's body. Because the motor and motor housing 211 can have a relatively high mass, it can be important to ensure that the motor housing 211 is stably supported. In one implementation, therefore, the motor housing 211 can be supported by the patient's body by way of the sliding member 213 and the connector 291 shown in FIG. 4. The sliding member 213 can slide along a track 214 located on a portion of the motor housing 211, such that relative motion between the motor assembly 206 and the patient does not decouple the sliding member 213 from the patient's body. The sliding member 213 and connector 291 can therefore be configured to provide a structural interface between the motor housing 206 and a platform for supporting the motor housing 211. As explained above, in some arrangements, the platform supporting the motor housing 211 can be the patient, since the motor housing 211 may be positioned quite close to the insertion point. In other arrangements, however, the platform supporting the motor housing 211 may be an external structure.

To couple the drive assembly 203 to the driven assembly 201, the clinician or user can insert the proximal portion of the flow diverter 205 into the opening 202 in the cap 212 of the motor housing 212. After passing through the opening 202, the proximal portion of the flow diverter can reside within a recess formed within the motor housing 211. In some implementations, a securement device is configured to lock or secure the drive assembly 203 to the driven assembly 201 once the driven assembly 201 is fully inserted into the drive assembly 203. In other implementations, the securement device can be configured to secure the drive assembly 203 to the driven assembly 201 by inserting the driven assembly 201 into the drive assembly 203 and then rotating the drive assembly 203 with respect to the driven assembly 201. In some implementations, coupling the drive assembly 203 to the driven assembly 201 may be irreversible, such that there may be no release mechanism to decouple the drive assembly 203 from the driven assembly 201. In implementations without a release mechanism, the catheter assembly 100A (including the driven assembly 201) and the motor housing 211 may be disposable components. In other implementations, however, a release mechanism may be provided to remove the drive assembly 203 from the driven assembly 201. The drive assembly 203 can thereby be used multiple times in some embodiments.

FIG. 6 illustrates the motor assembly 206 in the assembled state, e.g., after the drive assembly 203 has been secured to the driven assembly 201. When the drive assembly 203 is activated (e.g., a motor is activated to rotate an output shaft), the driven assembly 201, which is operably coupled to the drive assembly, is also activated. The activated driven assembly can cause the drive shaft 208 to rotate, which in turn causes the impeller to rotate to thereby pump blood through the patient.

FIGS. 7-8 illustrate the motor assembly 206 with one wall of the motor housing 211 removed so that various internal components in the housing 211 can be better illustrated. A motor 220 can be positioned within the housing 211 and mounted by way of a motor mount 226. The motor 220 can operably couple to a drive magnet 221. For example, the motor 220 can include an output shaft 222 that rotates the drive magnet 221. In some implementations, the drive magnet 221 can rotate relative to the motor mount 226 and the motor housing 211. Further, in some arrangements, the drive magnet 221 can be free to translate axially between the motor mount and a barrier 224. One advantage of the translating capability is to enable the drive magnet 221 and the driven magnet 204 to self-align by way of axial translation. The barrier 224 can be mounted to the motor housing 211 and at least partially within the cap 212 to support at least the drive magnet 221. In other implementations, the drive assembly 203 can comprise a plurality of motor windings configured to induce rotation of the drive magnet 221. In still other embodiments, motor windings can operate directly on a driven magnet within the driven assembly 201. For example, the windings can be activated in phases to create an electric field and thereby commutate the driven magnet.

In FIG. 8, the drive magnet 221 is illustrated in phantom, such that the driven magnet 204 can be seen disposed within the drive magnet 221. Although not illustrated, the poles of the drive magnet 221 can be formed on an interior surface of the drive magnet 221, and the poles of the driven magnet 204 can be formed on an exterior surface of the driven magnet 204. As the drive magnet 221 rotates, the poles of the drive magnet 221 can magnetically engage with corresponding, opposite poles of the driven magnet 204 to cause the driven magnet 204 to rotate with, or follow, the drive magnet 221. Because the driven magnet 204 can be mechanically coupled to the drive shaft 208, rotation of the drive magnet 221 can cause the driven magnet 204 and the drive shaft 208 to rotate at a speed determined in part by the speed of the motor 220. Furthermore, when the driven magnet 204 is inserted into the drive magnet 221, the poles of each magnet can cause the drive magnet 221 and the driven magnet 204 to self-align. The magnetic forces between the drive magnet 221 and the driven magnet 204 can assist in coupling the drive assembly 203 to the driven assembly 201.

Turning to FIG. 9, a 3D perspective view of various components at the interface between the drive assembly 203 and the driven assembly 201 is shown. Various components have been hidden to facilitate illustration of one means to secure the drive assembly 203 to the driven assembly 201. A first securement device 240 is illustrated in FIG. 9. The first securement device can comprise a first projection 240 a and a second projection 240 b. Furthermore, a locking recess 244 can be formed in the cap 212 around at least a portion of a perimeter of the opening 202. A lip 242 can also extend from the perimeter at least partially into the opening 202. As shown, the lip 242 can also extend proximally from the locking recess 244 such that a step is formed between the locking recess 244 and the lip 242. Further, a flange 246 can be coupled to or formed integrally with the flow diverter housing 207. In certain embodiments, the flange 246 can include a plurality of apertures 247 a, 247 b, 247 c, 247 d that are configured to permit tubes and cables to pass therethrough to fluidly communicate with lumens within the flow diverter 205. In some implementations, three tubes and one electrical cable can pass through the apertures 247 a-d. For example, the electrical cable can be configured to electrically couple to a sensor within the catheter assembly 100A, e.g., a pressure sensor. The three tubes can be configured to carry fluid to and from the catheter assembly 100A. For example, a first tube can be configured to carry infusate into the catheter assembly 100A, a second tube can be configured to transport fluids to the pressure sensor region, and the third tube can be configured to transport waste fluid out of the catheter assembly 100A. Although not illustrated, the tubes and cable(s) can pass through the apertures 247 a-d of the flange 246 and can rest against the motor housing 211. By organizing the routing of the tubes and cable(s), the apertures 247 a-d can advantageously prevent the tubes and cable(s) from becoming entangled with one another or with other components of the catheter pump system.

When the driven assembly 201 is inserted into the opening 202, the first and second projections 240 a, 240 b can pass through the opening and engage the locking recess 244. In some implementations, the projections 240 a, 240 b and the locking recess 244 can be sized and shaped such that axial translation of the projections 240 a, 240 b through the opening 202 causes a flange or tab 248 at a distal end of each projection 240 a, 240 b to extend over the locking recess 244. Thus, in some embodiments, once the projections 240 a, 240 b are inserted through the opening 202, the tabs 248 at the distal end of the projections 240 a, 240 b are biased to deform radially outward to engage the locking recess 244 to secure the driven assembly 201 to the drive assembly 203.

Once the driven assembly 201 is secured to the drive assembly 203, the flow diverter housing 207 can be rotated relative to the motor cap 212. By permitting relative rotation between the driven assembly 201 and the drive assembly 203, the clinician is able to position the impeller assembly 116A within the patient at a desired angle or configuration to achieve the best pumping performance. As shown in FIG. 9, however, the lip 242 can act to restrict the relative rotation between the driven assembly 201 (e.g., the flow diverter housing 207) and the drive assembly 203 (e.g. the cap 212 and the motor housing 211). As illustrated, the flange 246 and apertures 247 a-d can be circumferentially aligned with the projections 240 a, 240 b. Further, the lip 242 can be circumferentially aligned with the sliding member 213, the track 214, and the connector 291 of the motor housing 211. If the flange 246 and projections 240 a, 240 b are rotated such that they circumferentially align with the lip 242, then the tubes and cable(s) that extend from the apertures 247 a-d may become entangled with or otherwise obstructed by the sliding member 213 and the connector 291. Thus, it can be advantageous to ensure that the sliding member 213 and the connector 291 (or any other components on the outer surface of the housing 211) do not interfere or obstruct the tubes and cable(s) extending out of the apertures 247 a-d of the flange 246. The lip 242 formed in the cap 212 can act to solve this problem by ensuring that the flange 246 is circumferentially offset from the sliding member 213 and the connector 291. For example, the flow diverter housing 207 can be rotated until one of the projections 240 a, 240 b bears against a side of the lip 242. By preventing further rotation beyond the side of the lip 242, the lip 242 can ensure that the flange 246 and apertures 247 a-d are circumferentially offset from the sliding member 213, the track 214, and the connector 291.

In one embodiment, once the catheter assembly 100A is secured to the motor housing 211, the connection between the driven assembly 201 and the drive assembly 203 may be configured such that the drive assembly 203 may not be removed from the driven assembly 201. The secure connection between the two assemblies can advantageously ensure that the motor housing 211 is not accidentally disengaged from the catheter assembly 100A during a medical procedure. In such embodiments, both the catheter assembly 100A and the drive assembly 203 may preferably be disposable.

In other embodiments, however, it may be desirable to utilize a re-usable drive assembly 203. In such embodiments, therefore, the drive assembly 203 may be removably engaged with the catheter assembly 100A (e.g., engaged with the driven assembly 201). For example, the lip 242 may be sized and shaped such that when the drive assembly 203 is rotated relative to the driven assembly 201, the tabs 248 are deflected radially inward over the lip 242 such that the driven assembly 201 can be withdrawn from the opening 202. For example, the lip 242 may include a ramped portion along the sides of the lip 242 to urge the projections 240 a, 240 b radially inward. It should be appreciated that other release mechanisms are possible.

Turning to FIGS. 10A-10C, an additional means to secure the drive assembly 203 to the driven assembly 201 is disclosed. As shown in the 3D perspective view of FIG. 10A, a locking O-ring 253 can be mounted to the barrier 224 that is disposed within the motor housing 211 and at least partially within the cap 212. In particular, the locking O-ring 253 can be mounted on an inner surface of the drive or motor housing 203 surrounding the recess or opening 202 into which the driven assembly 212 can be received As explained below, the locking O-ring can act as a detent mechanism and can be configured to be secured within an arcuate channel formed in an outer surface of the driven assembly 201, e.g., in an outer surface of the flow diverter 205 in some embodiments. In other embodiments, various other mechanisms can act as a detent to secure the driven assembly 201 to the drive assembly 203. For example, in one embodiment, a spring plunger or other type of spring-loaded feature may be cut or molded into the barrier 224, in a manner similar to the locking O-ring 253 of FIGS. 10A-10C. The spring plunger or spring-loaded feature can be configured to engage the arcuate channel, as explained below with respect to FIG. 10C. Skilled artisans will understand that other types of detent mechanisms can be employed.

FIG. 10B illustrates the same 3D perspective of the drive assembly 203 as shown in FIG. 10A, except the cap 212 has been hidden to better illustrate the locking O-ring 253 and a second, stabilizing O-ring 255. The O-ring 255 is an example of a damper that can be provided between the motor 220 and the catheter assembly 100A. The damper can provide a vibration absorbing benefit in some embodiments. In other embodiment, the damper may reduce noise when the pump is operating. The damper can also both absorb vibration and reduce noise in some embodiments. The stabilizing O-ring 255 can be disposed within the cap 212 and can be sized and shaped to fit along the inner recess forming the inner perimeter of the cap 212. The stabilizing O-ring 255 can be configured to stabilize the cap 212 and the motor housing 211 against vibrations induced by operation of the motor 220. For example, as the motor housing 211 and/or cap 212 vibrate, the stabilizing O-ring 255 can absorb the vibrations transmitted through the cap 212. The stabilizing O-ring 255 can support the cap 212 to prevent the cap from deforming or deflecting in response to vibrations. In some implementations, the O-ring 255 can act to dampen the vibrations, which can be significant given the high rotational speeds involved in the exemplary device.

In further embodiments, a damping material can also be applied around the motor 220 to further dampen vibrations. The damping material can be any suitable damping material, e.g., a visco-elastic or elastic polymer. For example, the damping material may be applied between the motor mount 226 and the motor 220 in some embodiments. In addition, the damping material may also be applied around the body of the motor 220 between the motor 220 and the motor housing 211. In some implementations, the damping material may be captured by a rib formed in the motor housing 211. The rib may be formed around the motor 220 in some embodiments.

Turning to FIG. 10C, a proximal end of the driven assembly 201 is shown. As explained above, the flow diverter 205 (or the flow diverter housing in some embodiments) can include an arcuate channel 263 formed in an outer surface of the flow diverter 205. The arcuate channel 263 can be sized and shaped to receive the locking O-ring 253 when the flow diverter 205 is inserted into the opening 202 of the drive assembly 203. As the flow diverter 205 is axially translated through the recess or opening 202, the locking O-ring 253 can be urged or slid over an edge of the channel 263 and can be retained in the arcuate channel 263. Thus, the locking O-ring 253 and the arcuate channel 263 can operate to act as a second securement device. Axial forces applied to the motor assembly 206 can thereby be mechanically resisted, as the walls of the arcuate channel 263 bear against the locking O-ring 253 to prevent the locking o-ring 253 from translating relative to the arcuate channel 263. In various arrangements, other internal locking mechanisms (e.g., within the driven assembly 201 and/or the drive assembly 203) can be provided to secure the driven and drive assemblies 201, 203 together. For example, the driven magnet 204 and the drive magnet 221 may be configured to assist in securing the two assemblies together, in addition to aligning the poles of the magnets. Other internal locking mechanisms may be suitable.

FIG. 10C also illustrates a resealable member 266 disposed within the proximal end portion of the driven assembly 201, e.g., the proximal end of the catheter assembly 100A as shown in FIG. 4. As in FIG. 4, the proximal guidewire opening 237 can be formed in the resealable member 266. As explained above with respect to FIG. 4, the guidewire 235 can be inserted through the proximal guidewire opening 237 and can be maneuvered through the patient's vasculature. After guiding the operative device of the pump to the heart, the guidewire 235 can be removed from the catheter assembly 100A by pulling the guidewire 235 out through the proximal guidewire opening 237. Because fluid may be introduced into the flow diverter 205, it can be advantageous to seal the proximal end of the flow diverter 205 to prevent fluid from leaking out of the catheter assembly 100A. The resealable member 266 can therefore be formed of an elastic, self-sealing material that is capable of closing and sealing the proximal guidewire opening 237 when the guidewire 235 is removed. The resealable member can be formed of any suitable material, such as an elastomeric material. In some implementations, the resealable member 266 can be formed of any suitable polymer, e.g., a silicone or polyisoprene polymer. Skilled artisans will understand that other suitable materials may be used.

FIG. 11 illustrates yet another embodiment of a motor assembly 206A coupled to a catheter assembly. In FIG. 11, a flow diverter is disposed over and coupled to a catheter body 271 that can include a multi-lumen sheath configured to transport fluids into and away from the catheter assembly. The flow diverter 205A can provide support to the catheter body 271 and a drive shaft configured to drive the impeller assembly. Further, the motor assembly 206A can include a motor 220A that has a hollow lumen therethrough. Unlike the embodiments disclosed in FIGS. 4-10C, the guidewire 235 may extend through the proximal guidewire opening 237A formed proximal to the motor 220A, rather than between the motor 220A and the flow diverter 205A. A resealable member 266A may be formed in the proximal guidewire opening 237A such that the resealable member 266A can close the opening 237A when the guidewire 235 is removed from the catheter assembly. A rotary seal 273 may be disposed inside a lip of the flow diverter 205A. The rotary seal 273 may be disposed over and may contact a motor shaft extending from the motor 220A. The rotary seal 273 can act to seal fluid within the flow diverter 205A. In some embodiments, a hydrodynamic seal can be created to prevent fluid from breaching the rotary seal 273.

In the implementation of FIG. 11, the motor 220A can be permanently secured to the flow diverter 205A and catheter assembly. Because the proximal guidewire opening 237 is positioned proximal the motor, the motor 220A need not be coupled with the catheter assembly in a separate coupling step. The motor 220A and the catheter assembly can thus be disposable in this embodiment. The motor 220A can include an output shaft and rotor magnetically coupled with a rotatable magnet in the flow diverter 205A. The motor 220A can also include a plurality of windings that are energized to directly drive the rotatable magnet in the flow diverter 205A.

FIGS. 12A-12B illustrate another embodiment of a motor coupling having a driven assembly 401 and a drive assembly 403. Unlike the implementations disclosed in FIGS. 4-10C, however, the embodiment of FIGS. 12A-12B can include a mechanical coupling disposed between an output shaft of a motor and a proximal end of a flexible drive shaft or cable. Unlike the implementations disclosed in FIG. 11, however, the embodiment of FIGS. 12A-12B can include a guidewire guide tube that terminates at a location distal to a motor shaft 476 that extends from a motor 420. As best shown in FIG. 12B, an adapter shaft 472 can operably couple to the motor shaft 476 extending from the motor 420. A distal end portion 477 of the adapter shaft 472 can mechanically couple to a proximal portion of an extension shaft 471 having a central lumen 478 therethrough. As shown in FIG. 12B, one or more trajectories 473 can be formed in channels within a motor housing 475 at an angle to the central lumen 478 of the extension shaft 471. The motor housing 475 can enclose at least the adapter shaft 472 and can include one or more slots 474 formed through a wall of the housing 475.

In some implementations, a guidewire (not shown in FIG. 12B) may pass through the guidewire guide tube from the distal end portion of the catheter assembly and may exit the assembly through the central lumen 478 near the distal end portion 477 of the adapter shaft 472 (or, alternatively, near the proximal end portion of the extension shaft 471). In some embodiments, one of the extension shaft 471 and the adapter shaft 472 may include a resealable member disposed therein to reseal the lumen through which the guidewire passes, as explained above. In some embodiments, the extension shaft 471 and the adapter shaft 472 can be combined into a single structure. When the guidewire exits the central lumen 478, the guidewire can pass along the angled trajectories 473 which can be formed in channels and can further pass through the slots 474 to the outside environs. The trajectories 473 can follow from angled ports in the adapter shaft 472. A clinician can thereby pull the guidewire through the slots 474 such that the end of the guidewire can easily be pulled from the patient after guiding the catheter assembly to the heart chamber or other desired location. Because the guidewire may extend out the side of the housing 475 through the slots, the motor shaft 476 and motor 420 need not include a central lumen for housing the guidewire. Rather, the motor shaft 476 may be solid and the guidewire can simply pass through the slots 474 formed in the side of the housing 475.

Furthermore, the drive assembly 403 can mechanically couple to the driven assembly 401. For example, a distal end portion 479 of the extension shaft 471 may be inserted into an opening in a flow diverter housing 455. The distal end portion 479 of the extension shaft 471 may be positioned within a recess 451 and may couple to a proximal end of a drive cable 450 that is mechanically coupled to the impeller assembly. A rotary seal 461 may be positioned around the opening and can be configured to seal the motor 420 and/or motor housing 475 from fluid within the flow diverter 405. Advantageously, the embodiments of FIGS. 12A-B allow the motor 420 to be positioned proximal of the rotary seal in order to minimize or prevent exposing the motor 420 to fluid that may inadvertently leak from the flow diverter. It should be appreciated that the extension shaft 471 may be lengthened in order to further isolate or separate the motor 420 from the fluid diverter 405 in order to minimize the risk of leaking fluids.

III. Examples of Guidewire Guides and Distal Tip Members

Turning to FIG. 13, further features that may be included in various embodiments are disclosed. FIG. 13 illustrates a distal end portion 300 of a catheter assembly, such as the catheter assembly 100A described above. As shown a cannula housing 302 can couple to a distal tip member 304. The distal tip member 304 can be configured to assist in guiding the operative device of the catheter assembly, e.g., an impeller assembly (which can be similar to or the same as impeller assembly 116A), along the guidewire 235. The exemplary distal tip member 304 is formed of a flexible material and has a rounded end to prevent injury to the surrounding tissue. If the distal tip member 304 contacts a portion of the patient's anatomy (such as a heart wall or an arterial wall), the distal tip member 304 will safely deform or bend without harming the patient. The tip can also serve to space the operative device away from the tissue wall. In addition, a guidewire guide tube 312, discussed above with reference to FIG. 4, can extend through a central lumen of the catheter assembly. Thus, the guidewire guide tube 312 can pass through the impeller shaft (not shown, as the impeller is located proximal to the distal end portion 300 shown in FIG. 13) and a lumen formed within the distal tip member 304. In the embodiment of FIG. 13, the guidewire guide tube 312 may extend distally past the distal end of the distal tip member 304. As explained above, in various embodiments, the clinician can introduce a proximal end of the guidewire into the distal end of the guidewire guide tube 312, which in FIG. 13 extends distally beyond the tip member 304. Once the guidewire 235 has been inserted into the patient, the guidewire guide tube 312 can be removed from the catheter assembly in some implementations.

The distal tip member 304 can comprise a flexible, central body 306, a proximal coupling member 308, and a rounded tip 310 at the distal end of the tip member 304. The central body 306 can provide structural support for the distal tip member 304. The proximal coupling member 308 can be coupled to or integrally formed with the central body 306. The proximal coupling member 308 can be configured to couple the distal end of the cannula housing 302 to the distal tip member 304. The rounded tip 310, also referred to as a ball tip, can be integrally formed with the central body 306 at a distal end of the tip member 304. Because the rounded tip 310 is flexible and has a round shape, if the tip member 304 contacts or interacts with the patient's anatomy, the rounded tip 310 can have sufficient compliance so as to deflect away from the anatomy instead of puncturing or otherwise injuring the anatomy. As compared with other potential implementations, the distal tip member 304 can advantageously include sufficient structure by way of the central body 306 such that the tip member 304 can accurately track the guidewire 235 to position the impeller assembly within the heart. Yet, because the tip member 304 is made of a flexible material and includes the rounded tip 310, any mechanical interactions with the anatomy can be clinically safe for the patient.

One potential problem with the embodiment of FIG. 13 is that it can be difficult for the clinician to insert the guidewire into the narrow lumen of the guidewire guide tube 312. Since the guidewire guide tube 312 has a small inner diameter relative to the size of the clinician's hands, the clinician may have trouble inserting the guidewire into the distal end of the guidewire guide tube 312, which extends past the distal end of the tip member 304 in FIG. 13. In addition, when the clinician inserts the guidewire into the guidewire guide tube 312, the distal edges of the guidewire guide tube 312 may scratch or partially remove a protective coating applied on the exterior surface of the guidewire. Damage to the coating on the guidewire may harm the patient as the partially uncoated guidewire is passed through the patient's vasculature. Accordingly, it can be desirable in various arrangements to make it easier for the clinician to insert the guidewire into the distal end of the catheter assembly, and/or to permit insertion of the guidewire into the catheter assembly while maintaining the protective coating on the guidewire.

Additionally, as explained herein, the cannula housing 302 (which may form part of an operative device) may be collapsed into a stored configuration in some embodiments such that the cannula housing is disposed within an outer sheath. When the cannula housing 302 is disposed within the outer sheath, a distal end or edge of the outer sheath may abut the tip member 304. In some cases, the distal edge of the outer sheath may extend over the tip member 304A, or the sheath may have an outer diameter such that the distal edge of the outer sheath is exposed. When the sheath is advanced through the patient's vasculature, the distal edge of the outer sheath may scratch, scrape, or otherwise harm the anatomy. There is a therefore a need to prevent harm to the patient's anatomy due to scraping of the distal edge of the sheath against the vasculature.

FIG. 14 is a side cross-sectional view of a distal tip member 304A disposed at a distal end 300A of the catheter assembly, according to another embodiment. Unless otherwise noted, the reference numerals in FIG. 14 may refer to components similar to or the same as those in FIG. 13. For example, as with FIG. 13, the distal tip member 304A can couple to a cannula housing 302A. The distal tip member 304A can include a flexible, central body 306A, a proximal coupling member 308A, and a rounded tip 310A at the distal end of the tip member 304A. Furthermore, as with FIG. 13, a guidewire guide tube 312A can pass through the cannula housing 302A and a lumen passing through the distal tip member 304A.

However, unlike the embodiment of FIG. 13, the central body 306A can include a bump 314 disposed near a proximal portion of the tip member 304A. The bump 314 illustrated in FIG. 14 may advantageously prevent the outer sheath from scraping or scratching the anatomy when the sheath is advanced through the patient's vascular system. For example, when the cannula housing 302A is disposed within the outer sheath, the sheath will advance over the cannula housing 302A such that the distal edge or end of the sheath will abut or be adjacent the bump 314 of the tip member 304A. The bump 314 can act to shield the patient's anatomy from sharp edges of the outer sheath as the distal end 300A is advanced through the patient. Further, the patient may not be harmed when the bump 314 interact with the anatomy, because the bump 314 includes a rounded, smooth profile. Accordingly, the bump 314 in FIG. 14 may advantageously improve patient outcomes by further protecting the patient's anatomy.

Furthermore, the guidewire guide tube 312A of FIG. 14 does not extend distally past the end of the tip member 306A. Rather, in FIG. 14, the central lumen passing through the tip member 304A may include a proximal lumen 315 and a distal lumen 313. As shown in FIG. 14, the proximal lumen 315 may have an inner diameter larger than an inner diameter of the distal lumen 313. A stepped portion or shoulder 311 may define the transition between the proximal lumen 315 and the distal lumen 313. As illustrated in FIG. 14, the inner diameter of the proximal lumen 315 is sized to accommodate the guidewire guide tube 312A as it passes through a portion of the tip member 304A. However, the inner diameter of the distal lumen 313 in FIG. 14 is sized to be smaller than the outer diameter of the guidewire guide tube 312A such that the guidewire guide tube 312A is too large to pass through the distal lumen 313 of the tip member 304A. In addition, in some embodiments, the thickness of the guidewire guide tube 312A may be made smaller than the height of the stepped portion or shoulder 311, e.g., smaller than the difference between the inner diameter of the proximal lumen 315 and the inner diameter of the distal lumen 313. By housing the guidewire guide tube 312A against the shoulder 311, the shoulder 311 can protect the outer coating of the guidewire when the guidewire is inserted proximally from the distal lumen 313 to the proximal lumen 315.

The embodiment illustrated in FIG. 14 may assist the clinician in inserting the guidewire (e.g., the guidewire 235 described above) into the distal end 300A of the catheter assembly. For example, in FIG. 14, the guidewire guide tube 312A may be inserted through the central lumen of the catheter assembly. For example, the guidewire guide tube 312A may pass distally through a portion of the motor, the catheter body, the impeller assembly and cannula housing 302A, and through the proximal lumen 315 of the tip member 304A. The guidewire guide tube 312A may be urged further distally until the distal end of the guidewire guide tube 312A reaches the shoulder 311. When the distal end of the guidewire guide tube 312A reaches the shoulder 311, the shoulder 311 may prevent further insertion of the guidewire guide tube 312 in the distal direction. Because the inner diameter of the distal lumen 313 is smaller than the outer diameter of the guidewire guide tube 312A, the distal end of the guidewire guide tube 312A may be disposed just proximal of the shoulder 311, as shown in FIG. 14.

The clinician may insert the proximal end of the guidewire (such as the guidewire 235 described above) proximally through the distal lumen 313 passing through the rounded tip 310A at the distal end of the tip member 304A. Because the tip member 304A is flexible, the clinician can easily bend or otherwise manipulate the distal end of the tip member 304A to accommodate the small guidewire. Unlike the guidewire guide tube 312A, which may be generally stiffer than the tip member 304A, the clinician may easily deform the tip member 304A to urge the guidewire into the distal lumen 313. Once the guidewire is inserted in the distal lumen 313, the clinician can urge the guidewire proximally past the stepped portion 311 and into the larger guidewire guide tube 312A, which may be positioned within the proximal lumen 315. Furthermore, since most commercial guidewires include a coating (e.g. a hydrophilic or antomicrobial coating, or PTFE coating), the exemplary guide tube and shoulder advantageously avoid damaging or removing the coating. When the wall thickness of the guidewire guide tube 312A is less than the height of the step or shoulder 311, the shoulder 311 may substantially prevent the guidewire guide tube 312A from scraping the exterior coating off of the guidewire. Instead, the guidewire easily passes from the distal lumen 313 to the proximal lumen 315. The guidewire may then be urged proximally through the impeller and catheter assembly until the guidewire protrudes from the proximal end of the system, such as through the proximal guidewire opening 237 described above with reference to FIG. 4.

IV. Examples of Access Ports

The guidewire guide tubes 312, 312A described above with reference to FIGS. 13 and 14 can be configured to receive a guidewire for positioning an impeller assembly 316A and cannula housing 302A in the heart of a patient, e.g., across the aortic valve of the patient. As explained with reference to FIGS. 13 and 14, the guidewire guide tubes 312, 312A may be removed at some point after the guidewire is inserted within the guidewire guide tube 312, 312A. For example, the guidewire guide tube 312, 312A may be removed before the catheter assembly is inserted through the vascular system of the patient, e.g., by a modified Seldinger technique. One reason for removing the guidewire guide tubes 312, 312A before insertion is that the guidewire guide tubes 312, 312A may be too stiff to safely and reliably traverse the anatomy. For example, the guidewire guide tubes 312, 312A may have a stiffness that does not easily bend around the aortic arch during insertion. Thus, for removable guidewire guides 312, 312A, the guidewire can be inserted through the guidewire guide tube 312 or 312A, and the guidewire guide tube 312, 312A can be removed from the catheter assembly before the catheter assembly is inserted into the anatomy and to the heart.

However, in some arrangements, it may be advantageous to provide a tubular access port or access channel that provides access to the heart during treatment. The access channel can comprise a body having a lumen therethrough, such as a tube or similar structure. In some embodiments, the access channel can comprise a guidewire guide configured to remain in the catheter pump (and therefore the patient's vascular system) during treatment. In some embodiments, the guidewire guide may be non-removable or permanent; in other embodiments, the guidewire guide can be removed by the clinician if required or desired. In some arrangements, the guidewire guide may be fixed or secured to the catheter assembly such that the guidewire guide remains coupled to the catheter assembly during insertion and during the treatment procedure (e.g., when the impeller rotates at operational speeds). Thus, in some embodiments, a guidewire can be inserted through the guidewire guide as explained above. The guidewire may be advanced through the vasculature of the patient to the desired treatment region (e.g., the left ventricle in some embodiments). The catheter assembly with the guidewire guide may pass over the guidewire through the vasculature of the patient to position the impeller assembly and cannula in a chamber of the heart. The guidewire can be removed before operation of the pump, but the guidewire guide may remain disposed in the catheter assembly during the treatment procedure.

Advantageously, an access channel (e.g., a tube, such as a guidewire guide, comprising an internal channel) can give the clinician access to the heart during treatment. For example, if the cannula and impeller assembly become misaligned during treatment, the clinician can simply reinsert the guidewire through the access channel (e.g., a guidewire guide), and can move the catheter assembly to the desired position. In addition, one or more sensors can be disposed through the access channel to measure and transmit various fluid properties (e.g., pressure, temperature, flow rate, concentration, etc.) to a console or system controller. The access channel can also enable delivery of various chemicals and/or medications to the heart during a treatment procedure. Such medications may include, but are not limited to, antithrombotics, antiplatelets, anticoagulants (e.g. heparin or warfarin), superaspirins, thrombolytics, inotropes, vasopressors and vasodilators, diuretics, and anitretrovirals. The exemplary structure described above advantageously allows easy delivery of medication to the left ventricle or right ventricle, whichever the case may be, without requiring a separate catheter.

In some embodiments, the access channel can be similar to the guidewire guide 312A shown in FIG. 14. For example, an access channel 312B (e.g., a guidewire guide), also shown in FIG. 14, may extend distally the impeller assembly 316A and through at least a portion of the impeller and the tip member 304A. In particular, the access channel 312B can be disposed through a lumen of the catheter body 84 from a proximal portion of the catheter body 84, through a shaft of the impeller and can pass distal the impeller to the tip member 304A. However, unlike the guidewire guide 312A, which is removable, the access channel 312B may remain inside the catheter assembly during a treatment procedure. To at least partially enable the use of an access channel 312B (e.g., a guidewire guide that can remain in the patient and catheter assembly during operation), the access channel 312B may have a bending stiffness sufficiently low such that the access channel 312 (which may comprise a tubular structure having an internal channel or lumen) can safely and reliably traverse curves in the vasculature, e.g., the aortic arch. For example, the access channel 312B may comprise nitinol, an alloy comprising nickel and titanium, in various embodiments. The use of nitinol in the access channel 312B can allow the access channel 312B to remain in the anatomy during insertion and operation of the catheter assembly.

In particular, a guidewire can be inserted through the access channel 312B (e.g., a guidewire guide), as described above with respect to guidewire guide 312A. However, unlike the guidewire guide 312A described above, the access channel 312B can remain disposed in the catheter assembly as the catheter assembly is advanced through the vascular system of the patient. Further, the access channel 312B can remain disposed in the catheter assembly while the impeller rotates to pump blood through the catheter assembly. In some embodiments, the access channel 312B (e.g., a stationary guidewire guide) can remain substantially stationary relative to the impeller, such that the impeller rotates about the access channel 312B.

During operation of the impeller, the clinician may use the access channel 312B to access the heart. As explained above, the impeller assembly 92 may become misaligned during a procedure. To re-align and/or reposition the impeller assembly 92, the clinician may reinsert a guidewire through the access channel 312B, and can move the impeller assembly 92 proximally or distally relative to the guidewire to reposition the impeller assembly 92. Furthermore, the clinician may deliver medications or chemicals through the access channel 312B during a treatment. Various types of sensors may also pass through the access channel 312B to measure properties of blood flowing through the pump, such as pressure, flow rate, temperature, chemical or biological composition, etc.

FIG. 15 is a side view of an impeller assembly 316A having a cannula housing 302A, an impeller 317 disposed in the cannula housing 302A, and a tip member 304A. The components shown in FIG. 15 may be the same as or similar to the components illustrated in FIG. 14. A distal bearing support 318 can be disposed distal the impeller 317 and can provide radial support to the cannula housing 302A to maintain a tip gap between a free end of an impeller blade and an interior surface of the cannula housing 302A. Additional details of the distal bearing support 318 can be found throughout U.S. Patent Publication No. 2013/0303970 A1, and additional details of the impeller 317 can be found throughout U.S. Patent Publication No. 2013/0303830 A1, each of which is incorporated by reference herein in its entirety and for all purposes. A tubular access channel 312B or 312C can be disposed through the impeller 317 (e.g., through an impeller shaft to which the impeller 317 is coupled) and can pass distal the impeller 317. The access channel 312B, 312C can extend between the impeller 317 and the tip member 304A. The distal end of the access channel 312B, 312C can couple to the tip member 304A as shown in FIG. 14. The catheter assembly (e.g., including the impeller assembly 316A) can be configured such that when the impeller 317 rotates, the access channel 312B, 312C remains substantially stationary, e.g., the access channel 312B, 312C does not rotate with the impeller 317.

FIG. 16 is a side cross-sectional view of an access channel 312C disposed at a distal end 300A of the catheter assembly and configured to remain in the catheter assembly during treatment, according to another embodiment. As with the access channel 312B of FIG. 14, the access channel 312C may be configured to remain within the catheter assembly during insertion and operation of the impeller assembly 316A. For example, the access channel 312C can comprise nitinol, which may enable the tubular access channel 312C to traverse the anatomy (e.g., the aortic arch) to the heart.

The access channel 312C can include one or more windows 337A, 337B formed through a side wall of the access channel 312C. The windows 337A, 337B can provide fluid communication between an internal channel of the access channel 312C and blood flowing through the impeller assembly 92. For example, in some embodiments, a sensor connector 335 can pass through the channel of the access channel 312C, and a sensor tip 336 at a distal end of the connector 335 can be disposed adjacent a window 337A, 337B (e.g., window 337B as shown in FIG. 16). In some embodiments, the sensor tip 336 can comprise a pressure sensor for measuring the pressure of the blood flowing past the window 337A, 337B. For example, the pressure sensor can comprise a suitable fiber optic pressure sensor.

In other arrangements, the sensor tip 336 can be advanced through the access channel 312C to a location near a distal opening 339 of the access channel 312C. The distal opening 339 can provide fluid communication between the sensor tip 316 and distal opening 338 of the tip member 304A. For example, the sensor tip 316 can measure properties of the blood through the distal opening 339 of the access channel 312C and the distal opening 338 of the tip member 304A. In still other arrangements, the clinician can supply a chemical or medication to the heart during treatment by passing the chemical or medication through the internal channel of the tube 312C and into the patient by way of the window 337A or 337B or the distal openings 339, 338 of the tube 312C and tip member 304A, respectively. Although the windows 337A, 337B are shown as distal the impeller in FIG. 16, it should be appreciated that additional windows may be provided at other locations along the access channel 312B, 312C, e.g., proximal the impeller. Providing multiple windows in the access channel can enable access to the anatomy at various locations along the catheter assembly. For example, various fluid properties, such as pressure, may be measured at multiple points to map the properties along the catheter assembly.

FIGS. 17A and 17B are images of a proximal portion of a tubular access channel, which may be similar to the access channel 312B or 312C shown in FIGS. 14-16. The access channel 312B, 312C can extend from the impeller assembly 316A proximally through the elongate catheter body 84 and can exit proximally from the catheter assembly through the motor housing 211. In some embodiments, the access channel 312B, 312C can exit through one of the channels 247 a-d, or indeed through any suitable opening near the proximal portion of the catheter assembly. To accommodate a central, tubular access channel 312B, 312C, the motor housing 211 can comprise a proximal opening 341 formed through a proximal end portion of the housing 211. The motor can include hollow motor and/or drive shafts to accommodate the access channel 312B, 312C. As shown in FIG. 17A, the access channel 312B, 312C can extend proximally through the proximal opening 341 of the motor housing 211. In addition, to accommodate the access channel 312B, 312C, the barrier 224 described above may also have a barrier opening 342 through which the tubular access channel 312B, 312C can pass.

The access channel 312B, 312C disclosed herein can have walls sufficiently thick to support the tube 312B, 312C as it traverses the anatomy, e.g., the aortic arch. For example, the tube 312B, 312C can comprise a nitinol tube having a wall thickness of about 0.020″×0.025″, or about 0.020″×0.023″, in various arrangements. In addition, one or more fluid seals can be disposed along the guidewire guide 312B, 312C to prevent fluid from flowing out proximally of the catheter assembly. The seal(s) can be disposed near the impeller assembly 316A in some arrangements, while in other arrangements, the seal(s) can be disposed in the catheter body 84.

Accordingly, as explained herein, a tubular access channel can permit the clinician to have access to the heart during a treatment procedure, e.g. while the impeller is rotating. During a treatment procedure, for example, the clinician may insert a guidewire through an access channel (e.g., a guidewire guide tube). The access channel can be disposed in a catheter pump comprising a catheter body and an impeller assembly coupled to a distal portion of the catheter body. The clinician can advance the guidewire to a treatment location in a patient, such as a left ventricle of the patient's heart. The clinician can advance at least the impeller assembly, the catheter body, and the tubular access channel along the guidewire to position the impeller assembly at the treatment location. The clinician can activate the impeller assembly to pump blood while maintaining the access channel in the catheter pump.

The clinician can remove the guidewire from the patient before activating the impeller assembly. In some embodiments, the clinician can insert a sensor through the access channel and can advance the sensor to a location near the treatment location. The sensor can measure a property of the pumped blood. In some arrangements, the impeller assembly may become misaligned from the desired treatment location. The clinician can re-align the impeller assembly by deactivating the impeller assembly and inserting a second guidewire through the access channel while the access channel remains in the patient. The clinician can reposition the impeller assembly using the second guidewire. In some embodiments, the clinician can dispense a chemical or medication to the treatment location through the access channel. Advantageously, the access channel can provide the clinician with access to the heart during a treatment procedure.

Although the inventions herein have been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present inventions. It is therefore to be understood that numerous modifications can be made to the illustrative embodiments and that other arrangements can be devised without departing from the spirit and scope of the present inventions as defined by the appended claims. Thus, it is intended that the present application cover the modifications and variations of these embodiments and their equivalents. 

What is claimed is:
 1. A securing assembly for connecting a drive assembly to a driven assembly of a catheter pump, the securing assembly comprising: a motor housing; a flow diverter housing; a flow diverter positioned within the flow diverter housing, one of the flow diverter or the flow diverter housing comprising a securement device; and a cap coupled between the motor housing and the flow diverter housing, wherein the cap comprises a central opening and a locking recess extending circumferentially about the central opening, and wherein insertion of the flow diverter into the central opening causes securement device to engage the locking recess.
 2. The securing assembly of claim 1, wherein the securement device comprises a pair of projections.
 3. The securing assembly of claim 2 wherein each projection of the pair of projections comprises a tab at a distal end thereof configured to extend over the locking recess upon insertion of the pair of projections through the central opening.
 4. The securing assembly of claim 3, wherein the tabs of the pair of projections are configured to be biased in a radially outward direction to engage the locking recess.
 5. The securing assembly of claim 1, wherein the flow diverter housing comprises a flange having a plurality of apertures configured to permit at least one tube to pass therethrough.
 6. The securing assembly of claim 5, wherein the flange and the plurality of apertures are circumferentially aligned with the securement device.
 7. The securing assembly of claim 1, further comprising a barrier coupled to the motor housing and at least partially positioned within the cap, the barrier configured to support a drive magnet of the drive assembly.
 8. The securing assembly of claim 1, wherein the cap comprises a lip extending over the locking recess and radially inward towards the central opening.
 9. The securing assembly of claim 8, wherein a step is formed between the lip and the locking recess, wherein the step of the lip restricts relative rotation of the flow diverter housing and the motor housing.
 10. The securing assembly of claim 9, wherein the securement device comprises a pair of projections that each comprise a tab at a distal end thereof configured to extend over the locking recess upon insertion of the pair of projections through the central opening, wherein the lip comprises a ramped portion configured to bias the pair of projections radially inward such that the tabs are deflected radially inward over the lip to allow removal of the flow diverter from the central opening.
 11. The securing assembly of claim 9, wherein the motor housing comprises: a track extending along the motor housing; a sliding member slidably coupled to the track; and a connector coupled to the sliding member and configured to couple to a patient, wherein at least the track and the sliding member are circumferentially aligned with the lip.
 12. The securing assembly of claim 1, wherein the motor housing comprises: a track extending along the motor housing; a sliding member slidably coupled to the track; and a connector coupled to the sliding member and configured to couple to a patient, wherein the flow diverter housing comprises a flange having a plurality of apertures configured to permit at least one tube to pass therethrough, wherein the flange and the plurality of apertures are circumferentially aligned with the securement device and circumferentially offset from the track and the sliding member.
 13. A method of securing a drive assembly to a driven assembly of a catheter pump, the method comprising: coupling a flow diverter housing around a flow diverter, one of the flow diverter or the flow diverter housing including a securement device; coupling a cap to a motor housing, the cap including a central opening and a locking recess extending circumferentially about the central opening; inserting the flow diverter into the central opening of the cap; and engaging the securement device with the locking recess.
 14. The method of claim 13, wherein engaging the securement device comprises engaging a pair or projections with the locking recess.
 15. The method of claim 14, wherein engaging a pair or projections with the locking recess comprises biasing a tab located at the distal end of each projection of the pair of projections radially outward to engage the locking recess.
 16. The method of claim 13 further comprising coupling a flange to the flow diverter housing, the flange including a plurality of apertures configured to permit at least one tube to pass therethrough.
 17. The method of claim 16, wherein coupling a flange to the flow diverter housing comprises circumferentially aligning the flange with the securement device.
 18. The method of claim 13, further comprising rotating the flow diverter housing with respect to the cap wherein a lip of the cap extends over the locking recess and radially inward towards the central opening to form a step that limits further relative rotation of the flow diverter housing and the motor housing.
 19. The method of claim 18, further comprising rotating the motor housing with respect to the cap such that a track extending along the motor housing and a sliding member slidably coupled to the track are circumferentially aligned with the lip.
 20. The method of claim 18, further comprising rotating a pair of projections of the securement device relative to the cap such that a tab of each projection engages a ramped portion of the lip and biases the pair of projections radially inward over the lip to allow removal of the flow diverter from the central opening. 